// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_I18N_RTL_H_
#define BASE_I18N_RTL_H_

#include <string>

#include "base/compiler_specific.h"
#include "base/i18n/base_i18n_export.h"
#include "base/strings/string16.h"
#include "build/build_config.h"

namespace base {

class FilePath;

namespace i18n {

    const char16 kRightToLeftMark = 0x200F;
    const char16 kLeftToRightMark = 0x200E;
    const char16 kLeftToRightEmbeddingMark = 0x202A;
    const char16 kRightToLeftEmbeddingMark = 0x202B;
    const char16 kPopDirectionalFormatting = 0x202C;
    const char16 kLeftToRightOverride = 0x202D;
    const char16 kRightToLeftOverride = 0x202E;

    // Locale.java mirrored this enum TextDirection. Please keep in sync.
    enum TextDirection {
        UNKNOWN_DIRECTION = 0,
        RIGHT_TO_LEFT = 1,
        LEFT_TO_RIGHT = 2,
        TEXT_DIRECTION_NUM_DIRECTIONS = 3,
    };

    // Get the locale that the currently running process has been configured to use.
    // The return value is of the form language[-country] (e.g., en-US) where the
    // language is the 2 or 3 letter code from ISO-639.
    BASE_I18N_EXPORT std::string GetConfiguredLocale();

    // Canonicalize a string (eg. a POSIX locale string) to a Chrome locale name.
    BASE_I18N_EXPORT std::string GetCanonicalLocale(const std::string& locale);

    // Sets the default locale of ICU.
    // Once the application locale of Chrome in GetApplicationLocale is determined,
    // the default locale of ICU need to be changed to match the application locale
    // so that ICU functions work correctly in a locale-dependent manner.
    // This is handy in that we don't have to call GetApplicationLocale()
    // everytime we call locale-dependent ICU APIs as long as we make sure
    // that this is called before any locale-dependent API is called.
    BASE_I18N_EXPORT void SetICUDefaultLocale(const std::string& locale_string);

    // Returns true if the application text direction is right-to-left.
    BASE_I18N_EXPORT bool IsRTL();

    // Returns whether the text direction for the default ICU locale is RTL.  This
    // assumes that SetICUDefaultLocale has been called to set the default locale to
    // the UI locale of Chrome.
    // NOTE: Generally, you should call IsRTL() instead of this.
    BASE_I18N_EXPORT bool ICUIsRTL();

    // Returns the text direction for |locale_name|.
    // As a startup optimization, this method checks the locale against a list of
    // Chrome-supported RTL locales.
    BASE_I18N_EXPORT TextDirection
    GetTextDirectionForLocaleInStartUp(const char* locale_name);

    // Returns the text direction for |locale_name|.
    BASE_I18N_EXPORT TextDirection GetTextDirectionForLocale(
        const char* locale_name);

    // Given the string in |text|, returns the directionality of the first or last
    // character with strong directionality in the string. If no character in the
    // text has strong directionality, LEFT_TO_RIGHT is returned. The Bidi
    // character types L, LRE, LRO, R, AL, RLE, and RLO are considered as strong
    // directionality characters. Please refer to http://unicode.org/reports/tr9/
    // for more information.
    BASE_I18N_EXPORT TextDirection GetFirstStrongCharacterDirection(
        const string16& text);
    BASE_I18N_EXPORT TextDirection GetLastStrongCharacterDirection(
        const string16& text);

    // Given the string in |text|, returns LEFT_TO_RIGHT or RIGHT_TO_LEFT if all the
    // strong directionality characters in the string are of the same
    // directionality. It returns UNKNOWN_DIRECTION if the string contains a mix of
    // LTR and RTL strong directionality characters. Defaults to LEFT_TO_RIGHT if
    // the string does not contain directionality characters. Please refer to
    // http://unicode.org/reports/tr9/ for more information.
    BASE_I18N_EXPORT TextDirection GetStringDirection(const string16& text);

    // Given the string in |text|, this function modifies the string in place with
    // the appropriate Unicode formatting marks that mark the string direction
    // (either left-to-right or right-to-left). The function checks both the current
    // locale and the contents of the string in order to determine the direction of
    // the returned string. The function returns true if the string in |text| was
    // properly adjusted.
    //
    // Certain LTR strings are not rendered correctly when the context is RTL. For
    // example, the string "Foo!" will appear as "!Foo" if it is rendered as is in
    // an RTL context. Calling this function will make sure the returned localized
    // string is always treated as a right-to-left string. This is done by
    // inserting certain Unicode formatting marks into the returned string.
    //
    // ** Notes about the Windows version of this function:
    // TODO(idana) bug 6806: this function adjusts the string in question only
    // if the current locale is right-to-left. The function does not take care of
    // the opposite case (an RTL string displayed in an LTR context) since
    // adjusting the string involves inserting Unicode formatting characters that
    // Windows does not handle well unless right-to-left language support is
    // installed. Since the English version of Windows doesn't have right-to-left
    // language support installed by default, inserting the direction Unicode mark
    // results in Windows displaying squares.
    BASE_I18N_EXPORT bool AdjustStringForLocaleDirection(string16* text);

    // Undoes the actions of the above function (AdjustStringForLocaleDirection).
    BASE_I18N_EXPORT bool UnadjustStringForLocaleDirection(string16* text);

    // Returns true if the string contains at least one character with strong right
    // to left directionality; that is, a character with either R or AL Unicode
    // BiDi character type.
    BASE_I18N_EXPORT bool StringContainsStrongRTLChars(const string16& text);

    // Wraps a string with an LRE-PDF pair which essentialy marks the string as a
    // Left-To-Right string. Doing this is useful in order to make sure LTR
    // strings are rendered properly in an RTL context.
    BASE_I18N_EXPORT void WrapStringWithLTRFormatting(string16* text);

    // Wraps a string with an RLE-PDF pair which essentialy marks the string as a
    // Right-To-Left string. Doing this is useful in order to make sure RTL
    // strings are rendered properly in an LTR context.
    BASE_I18N_EXPORT void WrapStringWithRTLFormatting(string16* text);

    // Wraps file path to get it to display correctly in RTL UI. All filepaths
    // should be passed through this function before display in UI for RTL locales.
    BASE_I18N_EXPORT void WrapPathWithLTRFormatting(const FilePath& path,
        string16* rtl_safe_path);

    // Return the string in |text| wrapped with LRE (Left-To-Right Embedding) and
    // PDF (Pop Directional Formatting) marks, if needed for UI display purposes.
    BASE_I18N_EXPORT string16 GetDisplayStringInLTRDirectionality(
        const string16& text) WARN_UNUSED_RESULT;

    // Strip the beginning (U+202A..U+202B, U+202D..U+202E) and/or ending (U+202C)
    // explicit bidi control characters from |text|, if there are any. Otherwise,
    // return the text itself. Explicit bidi control characters display and have
    // semantic effect. They can be deleted so they might not always appear in a
    // pair.
    BASE_I18N_EXPORT string16 StripWrappingBidiControlCharacters(
        const string16& text) WARN_UNUSED_RESULT;

} // namespace i18n
} // namespace base

#endif // BASE_I18N_RTL_H_
